The Green Revolution and Urbanization. The speed of urbanization can be affected by many factorsówars, droughts, revolutions, depressions, booms, for example. It is often difficult to foresee over a decade or so what will influence this speed. The Green Revolution provides an illustration of this point. A transformation only recently begun, it has not spread to all developing countries, and its long-term success is still problematical; yet the Green Revolution promises to have a considerable impact upon the volume of rural-urban migration and therefore upon the rate of urbanization. Because it is based upon technological innovation, primarily the use of fertilizers, the Green Revolution favors the larger, more modern, and commercially oriented farms. This development, in conjunction with high rates of population increase in rural areas, can be expected to increase out-migration to urban areas. (Whether there will be mass migration of whole families and of all ages or simply an intensified exodus of the traditionally migration-prone groupóthe young adultsóis not clear.)
In addition to its possible effect upon the size and composition of migration streams, the Green Revolution may affect future levels of urbanization, because the growing urban population can be provisioned better from internal sources. Higher agricultural productivity makes possible a higher level of urbanization.
Migration-the Major Mechanism of Urbanization
There are various combinations of fertility, mortality, and migration that can cause the rapid growth of urban populations. But it is most common in time and space that the major contributor is rural-urban migration.
To understand the urbanization process in a given region, it is important to know how many people are moving from one place to another. Data on migration streams are indispensable. It is equally important, however, to know who is migrating. Demographic characteristics (age, sex, marital status, etc.) and socioeconomic characteristics (education, occupation, etc.) are needed to understand the impact of migration on both communities of origin (rural and urban) and the urban communities of destination. All these factors affect incorporation of migrants into the urban milieu.
Return migration is another aspect of internal migration that is best understood by reference to community of origin and of destination. Reliable information on its magnitude is generally lacking, but it represents a significant proportion of all migrations. To an extent still not determined, return migration acts as a sorting mechanism, returning the less successful and least satisfied migrants back to their communities of origin.
The effect of in-migration on the further growth of urban population depends upon the reproductive behavior of the migrants, a complex phe-this rule involve the breakdown of the social order, aswith an increase in the number of school-aee children, the sovern-oer caoita costs of sovern-shine returns: it would notelated collective consumption needs would stay largely unchanged for the better part of a decade, and